Method of making bireactive compounds containing oxirane unit and ethanethiol group in same molecule



United States Patent METHOD OF MAKING BIREACTIVE COMPOUNDS CONTAININGOXIRANE UNIT AND ETHANE- THIOL GROUP IN SAME MOLECULE William R. Nummy,Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., acorporation of Delaware No Drawing. Original application Oct. 16, 1961,Ser. No. 145,470. Divided and this application Mar. 4, 1963, Ser. No.262,391

2 Claims. (Cl. 204I58) The present application is a division of thecopending application for United States Letters Patent having Serial No.145,470, filed October 16, 1961, now United States Patent No. 3,217,015,patented November 9, 1965, which patent application contained subjectmatter divided from now abandoned application for United States LettersPatent having Serial No. 771,247, filed November 3, 1958, which,'inturn, embraced subject matter divided from and was acontinuation-in-part of the application for United States Letters Patenthaving Serial No. 571,848 which was filed on March 15, 1956, nowabandoned.

The present invention resides in and contributes to the organic chemicalarts. In particular, the present invention is concerned with novelbireactive compounds and to a method for their preparation. inventionrelates to monomeric, bireactive compounds which contain an oxirane ringor unit (i.e., an epoxy group) arranged in the same molecule with anethanethiol group.

Bireactive compounds according to the invention are comprised of those,in the monomeric and unpolyrnerized form, having the general formula:

wherein G is a bivalent polyether (frequently a diether) radical from aglycol obtained, as it were, by removal of the terminal,oxygen-connected hydrogens therefrom. Advantageously, G is a bivalentdiether radical from a glycol having from 2 to about 6 carbon atoms inits molecule. Illustrative of the general type of arrangement of suchradicals are:

(a) OCH O-, in which x is an integer from 2 to about 6 (as in thedivalent butane diol radicals of the More specifically, this oi thehydrogen sulfide.

structure: {-O-CH CH CH CH -O) and homologous divalent polymethylenediol radicals of from 2 to about 6 carbon atoms); (b) O{CH CH -O) inwhich y is an integer from 1, or, to avoid duplication of certain of thespecies of type (a) above, from 2 to 3 (as in the radicals from ethyleneglycol and the lower polyethylene glycols); and (c) -O{-CH CH(CH )-O-)in which 2 is an integer from 1 to 2 (as in the radicals from propyleneglycol and dip-ropylene glycol). As is apparent, the radicalsrepresented by the symbol G may frequently consist of those having oneor more inner oxygen or heteroether linkages in their constitution.

The bireactive compounds of the Formula I may conveniently be preparedby a method in accordance with the present invention which comprisesconverting a corresponding vinyl glycidyl ether to the desired product.Such vinyl ethers may be obtained by first forming an alkali metalalcoholate of a monovinyl ether of a glycol and reacting it withepichlorohydrin. To such intermediate (or, actually, for presentpurposes, starting) product the thiol group is introduced to themolecule as hereinafter delineated. Advantageously, in preparing thecorresponding vinyl glycidyl ether of the glycol, the alcoholate may beobtained from the vinyl ether with a solid alkali metal caustic materialsuch as solid potassium hydroxide. The desired thiol-containingcompounds are prepared readily 'ice from the epoxidized intermediate bysubjecting a vinyl radical-containing bireactive compound of the typereferred to (i.e., the vinyl glycidyl ether of a glycol) to theso-called abnormal addition of hydrogen sulfide under free radicalgenerating conditions.

The reaction to form the intermediate (or starting) corresponding vinylglycidyl ether of the glycol may be conducted under any desired pressureat a temperature between about 20v C. and C. and, more advanta'geously,at a temperature between about 20 C. and 50 C. in order to minimize thepolymerizing tendency of the corresponding vinyl compound which isobtained. It is beneficial to employ at least about 2 moles of themonovinyl ether of a glycol and about 2 moles of the epichlorohydrin permole of the solid caustic in order to prepare the vinyl glycidyl etherof the glycol. Preferably, about 3 moles of the monovinyl ether of aglycol and about 3 moles of the epichlorohydrin are employed per mole ofsolid caustic. The excessive amount of the monovinyl ether functions asa'solvent for the alkali metal alcoholate of the other which ispreliminarily formed for subsequent reaction. The greater proportion ofepichlorohydrin minimizes the reactive propensity of the epoxy groupattached in the molecule of the corresponding bireactive vinylcompoundin the course of its preparation. Anhydrous conditions arepreferred for such a reaction.

The vinyl glycidyl glycol ether-forming reaction can ordinarily becompleted within one or two hours. It is only limited as to time by thatperiod which may be necessary, as a practical matter, to introduce thetotal amount of thefepichlorohydrin while maintaining a desiredtemperature during. the exothermic reaction which occurs. The freeradical generating conditions which are beneficial for preparing thepresently contemplated thiol-containing bireactive compounds of theFormula I from the corresponding vinyl glycidyl ether of the glycol byabnormal addition of hydrogen sulfide thereto may be provided, forexample, under the excitation of actinic light. It is usually desirablefor optimum results in the abnormal addition to employ at least astoichiometric quantity Generally, best results are achieved whenconsiderable excesses of the hydrogen sulfide are utilized.Advantageously, actinic light having a greater wave length than about3,000 A. may be empl-oyed, particularly when the reaction is assisted byemployment of a suitable photosensitizing amount of a photosensitizer inthe reaction mass. Such photosensitizers as one selected from the groupconsisting of 2,5- dichlorostyrene, divinylbenze'ne, anthracene',fluorene, mixtures thereof and the like are utilized with great benefitfor suchpurpose. Ordinarily, anamount of the photosensitizer betweenabout 0.01 and 5.0 percent by weight (more advantageously, an amountbetween about 0.1 and 1.0- percent by weight) of photosensitizer may besatisfactorily utilized for such purposes.

The bireactive compounds of the present invention are especially usefulfor the preparation of polymer produets which oftentimes haveelastomeri'c' properties and are particularly well adapted foremployment as adhesives'or binders of the pressure-sensitive, relativelydis joinable variety. Such polymers are well suited in many instancesfor joining, especially with the indicated type of bond, such diversematerials as woodto metal (as aluminum) or glass, etc. In addition, thepolymeric products of the present invention have good utility in and forthe formulation, following generally conventional techniques andpreparations, of coating compositions and in preparing polymer blendswith (or to modify) other polymeric materials to obtain relativelyelastomeric prod* nets of oftentimes highly desirable characteristics.Certain of the polymer products, particularly when carefullyrubberyproducts thatquite often are adapted tobeing" molded or otherwisefabricated, or shaped to conform upon setting up during polymerizationto the container in which they'are polymerized, so as to'produce'usefularticles andconstructions for many of a wide varietyof purposes.

'l The polymerizationo'f the monomeric, bireactive compounds of theFormula .I can ordinarily be b'estefliected under the influence of basiccatalysts (such as diethylene triamine.or,N,N-dimethyl dodecylamine andthe; like). The polymerizations may be conducted by .=using :mass (orbulk) polymerization procedures. Since the-polymerization reactionunderbasic catalysis is exothermic in nature,'it may generally beinitiated at room temperature. However, if desired, elevated startingand polymerization temperatures (as in the range from say 60-100 C. orso) may also be employed. The time that may be required forpolymerization of a given system may vary from a fewhours or less (downtomatters of mere minutes) to several days, depending (among otherfactors as iwill be apparent to those with the skill of their calling)on the specific materials and proportions involved as well as theparticular conditions under which the reaction is "accomplished. I

Further manifestations of the present contribution are provided in andby the following representative "illustrations which are merely docentin nature'and are-not intended to be limiting or restrictive of theinvention.

. Illustration A; 7

' About 150 grams of the monovinyl ether of diethylene glycol and 21.6grams of potassium hydroxide in pellet form were stirred together untildissolution of the solid caustic material had occurred. About 10milliliters of the ether was then removed from the mass by vacuumdistillation in order to insure the complete abs enceof water therein.About 96 grams of epichlorohydrin was then added with stirring inuniform increments over a period of about one hour so as to maintain atemperature of about -80 C. in the reaction mass. After the entirequantity of the epichlorohydrin had been added, the reaction mass wasmaintained at about 80 C. for an additional one hour period. At the endof this time, the unreacted epichlorohydrin was removed by distillationand the potassium chloride salt which had formed in the reaction masswas filtered off. The balance of the reaction mass was fractionallydistilled under vacuum. About 35.5 grams of the vinyl glycidyl ether. ofdiethylene glycol, having the formula: 1

ongorhcmo 011201120 cnzomoon=om was thereby obtained under apressure ofabout 1 millimeter of mercury in the temperature range from about 90 to93 C. The yield of this material, based on the quantity of the causticemployed, was about 50 percent.

About 200 grams of the thereby prepared vinyl glycidyl either ofdiethylene glycol and 750 grams of hydrogen sulfide werethen placed in apressure reactor having a capacity of about 1500 cubic centimeters underan autogenous pressure of about 220-250 pounds per square inch (gauge).About 0.5 gram of 2,5-dichlorostyrene was incorporated in the reactionmass as a photosensitizer. The pressure reactor had a built-in well ofPyrex glass which permitted illumination of the contents. It was alsoequipped with an eflicient agitating mechanism. 'A General Electric TypeAH-6 lamp was employed in the well as a source of ultraviolet radiationto obtain a substantial preponderance of light waves through the glasswell having a wave length greater than about 3,000 A. The reaction masswas subjected to about 30 minutes of radiation from the ultravioletsource while it was being maintained at atemperature of about 0-10'C. Atthe end of this period the reaction was terminated. Excess hydrogensulfide was removed by evaporation. The reaction mass "was subsequentlysubjected to'a vacuum distillation:

About 1'15 grams of a monomeric epoxymercaptan bireactive compound wasobtained as the fraction boiling at a temperature of about 150 C. underabout 1 millimeter of mercury pressure. ltwas identified as being thecompound 2 -(2-(2-(2,3-epoxypropoxy)ethoxy-)ethoxy) ethanethiol and hadthe general formula:

CHTCHCHzOCHzOHaOCHaCHzOOHaCHaSH (I Illustration B" To a quantitydistilled sample of 2-(2-(2-(2,3-epoxypropoxy)ethoxy-)ethoxy)ethanethiol of the Formula II (boiling from 130 to 140 C. under anabsolute mercury pressure of about 0.4 millimeter) there was added, atroom temperature, a trace (approximately 0.1 weight percent on theweight of the mass) of N,Ndimethyl dodecylamine. Within a few minutes,an easily evident exothermic reaction commenced. The viscosity of theliquid increased rapidly until a rubbery polymer product of thepolymerized bireactive compound was obtained. The polymer product, whichhad relatively low molecular weight, was a somewhat tacky andadhesivematerial that had excellent cold flow and easy spreadingproperties.

When the thereby-obtained polymerproduct is spread coatedto about a 5mil thickness over a A inch by 8 inch by 8 inch panel of yellow pinewood over which is pressed a similatly'sized sheet of'clean aluminum,there is provided an excellent wood-to-metal adhesive bond capable ofbeingfirmly established by merely moderate pressing together (under anaverage applied pressure of, say 110 pounds-per square inch) of thealuminum sheet to the coated wood panel. The wood and metal aresecurely' and rigidly joined by the polymeric adhesive yet are capableof being cleanly separated or delaminated without undue difiiculty. Thisis accomplished by the simple operation of prying apart the bondedpieces, using a knife or other blade to facilitate the disjoinder.Similar results are obtained when using'the polymer as a yieldable,pressure-sensitive type adhesive for joining wood to glass.

Illustration C About r100 parts by weight of the same monomericethanethiol glycidyl ether compound prepared as in the firstillustration and subsequently purified are mixed with about 1 part byweight of diethylene triamine in a large cylindrical container having aninternal diameter of about an inch and a height of 8 inches. Anexothermic reaction occurs almost immediately. A relatively tough yetrubbery solid polymer product is obtained having the same shape as thecontainer in which the polymerization is performed and useful forvarious applications requiring such configurations.

Results similar to the foregoing are obtained when the general procedureof Illustration A is repeated to manufacture any other of the compoundsof the Formula I v and when such monomeric products are converted, inthe above-demonstrated or like ways, to various polymer products. I

What is claimed is: 1. Method of manufacturing a bireactive compoundhaving the general structure:

O T OJEkOHPG-GHQCmSH (I) wherein G is a bivalent polyether radicalselected from the group consisting of those of the structural formulae:-.OtCH O, in which x is an integerfrom 1 to 6;. .-0{-CH CH O-} in whichy is an integer from 2 to 3; and O(-CH CH(CH )O-} in which 2 is aninteger from 1 to 2, which method comprises mixing hydrogen sulfide witha vinyl glycidyl ether of the general structure:

in which G is as above defined, then subjecting said mixture to exposureof actinic light whereby there is produced excitation and abnormaladdition of hydrogen sulfide across the ethylenically unsaturatedlinkage of the vinyl group in said ether until at least a portion ofsaid ether is converted to said compound of the Formula I.

2. In the method of claim 1, subjecting the vinyl glycidyl ether toabnormal addition of hydrogen sulfide under the excitation of actiniclight having a greater wave length than about 3,000 A. and in thepresence of a photosensitizing amount of a photosensitizer selected fromthe group consisting of 2,5-dichlorostyrene, divinylbenzene, anthraceneand fluorene.

6 References Cited by the Examiner UNITED STATES PATENTS 2,314,0393/1943 Evans et a1. 260348 5 2,398,479 4/1946 Vaughn et a1. 204-1582,398,480 4/1946 Vaughn et a1. 204-158 2,824,112 2/1958 McMinrI 260-348WINSTON A. DOUGLAS, Primary Examiner. H. s. WILLIAMS, JOHN H. MACK,Examiners.

1. METHOD OF MANUFACTURING A BIREACTIVE COMPOUND HAVING THE GENERALSTRUCTURE: